Vehicle alternators produce three-phase alternating current that is rectified into a direct current. The associated voltage can be stored in a battery of a vehicle or be used directly by the electrical circuit of the vehicle, which is supplied with a direct current (DC) voltage. Rectification of the three-phase alternating current may be obtained by means of a rectifier bridge having six power switches. The rectification of an n-phase alternating current may be obtained by means of a rectifier bridge having 2*n power switches. Commonly, a rectification of 6-phase alternating current is found in alternators and therefore these alternators require a rectifier bridge having 12 power switches. Other lesser common alternators have a 5-phase or 7-phase alternating current and therefore respectively require a rectifier bridge having 10 or 14 power switches. As well known to those skilled in the art, more switches than 2*n may be utilized if switches are connected in parallel or if switches are utilized to rectify the neutral point of the stator winding. Most commonly, the type of power switch is a diode, but other types of switches may also be utilized such as FETS, MOSFETS or any other type of electric switch. Three of these switches are the positive switches, and these positive switches are connected between the phase terminals of the stator windings of the alternator and the positive terminal B+ of the alternator which is connected to the battery and the electrical circuit of the vehicle. Three further switches, namely the negative switches, are connected between electrical ground or earth of the vehicle and the aforementioned phase terminals of the stator windings.
The positive and negative switches make up a rectifier bridge that is subjected to high current. Hence, it is necessary to cool the switches in the most effective way possible. To this end, the switches are commonly mounted on metal members arranged on the outside of the alternator. The metal members not only serve as mounting members, but also serve as a heat sink designed to dissipate heat produced by the switches. The switches are typically grouped on two carrier members, one of which is reserved for the positive switches (i.e., a positive carrier member), and the other for the negative switches (i.e., a negative carrier member). The rectifier switches may be inserted by pressure in receiving bore holes of the carrier member/heat sink, or may be soldered to the carrier member using appropriate solder alloys. The end wires connected to the rectifier switches enable the rectifier switches to be connected to the leads of the stator windings of the electric machine.
In such an alternator arrangement where the rectifier bridge is mounted on carrier members, the negative carrier member is connected to a vehicle ground/battery return path. The vehicle ground/battery return path is often provided by the engine itself, including a path through the alternator housing. Therefore, the negative carrier member may be provided by the alternator housing itself. On the other hand, the positive carrier member is connected to a terminal and an electrical cable connects the terminal to the positive terminal of the vehicle battery. The negative carrier member must be electrically isolated from the positive carrier member. Accordingly, an insulator must be inserted between the positive carrier member and the negative carrier member. The insulator is typically configured to provide both electrical isolation and a desired spatial separation between the positive and negative carrier members.
FIG. 8 shows a cross-sectional view of an end portion (e.g., a slip ring end) of a typical alternator including an alternator housing 112 serving as the negative carrier member, and a heat sink 130 serving as the positive carrier member. A terminal assembly 140 sits on top of the positive carrier member and includes posts that extend through an opening of positive carrier member. The terminal assembly includes electrical traces 46 providing electrically conductive lines that make connections from the switches 128 to the leads of the stator windings of the electric machine. As noted previously, the positive carrier member 130 must be electrically isolated from the negative carrier member 112. Therefore, an insulator 200 is positioned between the positive carrier member 130 and the negative carrier member 112. The insulator is comprised of an insulating material such as polyphenylene sulfide (PPS), and must be sufficient in thickness to provide a desired separation between the positive carrier member and the negative carrier member. The insulator, terminal assembly, positive carrier member, and negative carrier member are fixed together by bolts, rivets or other fasteners that may extend from the terminal assembly to the housing. As shown in FIG. 8, a bolt 148 has a head that abuts the terminal assembly and a threaded portion that extends through the terminal assembly and positive carrier member and is threaded in a receptacle in the negative carrier member (i.e., the alternator housing).
While the foregoing arrangement provides an effective arrangement for mounting an electronics package to an alternator, there are numerous parts which are relatively expensive, and each of these parts must be maintained and handled during the manufacturing process. Accordingly, it would be desirable to provide an alternator arrangement having an electronics package that may be mounted to the alternator with fewer parts. It would also be advantageous if the alternator arrangement resulted in reduced component costs and reduced complexity during the manufacturing process.